The present disclosure relates generally to an apparatus for interrupting a short circuit in a circuit breaker, and particularly to a cassette having a slot motor and line strap arrangement for enhancing short circuit interruption performance.
Circuit breakers are used today in electrical distribution systems for protecting electrical circuits, and may be single-phase or multi-phase devices having a variety of ampere and voltage ratings, such as 15-1200 amps at 120-600 volts ac or 500 Volts DC for example. To respond to a short circuit condition, circuit breakers employ trip units, which may be thermal, magnetic, pressure actuated, or electronic in nature, and may be coupled to contact arms that are of a blow open or non-blow open arrangement. With blow open contact arm arrangements, a short circuit condition causes the contact arms to blow open independent of the circuit breaker operating mechanism and independent of the trip unit action. Advancements in circuit breaker design has led to an arrangement of modular cassettes having blow open contact arms, with each cassette being contained within a circuit breaker housing, and with each cassette being in operable communication with an electronic trip or mechanical Thermal/Magnetic trip unit and an operating mechanism. The blow open contact arm arrangement provides for a rapid response to a short circuit condition, while the electronic trip unit or mechanical trip unit arrangement provides for a multi-functional tripping device. However, as market demands increase, so do the demands on short circuit interruption performance. Accordingly, there is a need for advances in the field of short circuit interruption technology where a blow open contact arm can more rapidly respond to the onset of a short circuit fault condition.